[Intel-gfx] [PATCH 3/3] drm/i915: Warn in debug builds of incorrect usages of ptr_pack_bits

[Tvrtko Ursulin]

From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

GEM_BUG_ON if the packed bits do not fit into the specified width.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/i915_utils.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h
index 402d995b94a5..49b9de753c42 100644
--- a/drivers/gpu/drm/i915/i915_utils.h
+++ b/drivers/gpu/drm/i915/i915_utils.h
@@ -83,8 +83,10 @@
 	(typeof(ptr))(__v & -BIT(n));					\
 })
 
-#define ptr_pack_bits(ptr, bits, n)					\
-	((typeof(ptr))((unsigned long)(ptr) | ((bits) & (BIT(n) - 1))))
+#define ptr_pack_bits(ptr, bits, n) ({					 \
+	GEM_BUG_ON((bits) & -BIT(n));					 \
+	((typeof(ptr))((unsigned long)(ptr) | ((bits) & (BIT(n) - 1)))); \
+})
 
 #define page_mask_bits(ptr) ptr_mask_bits(ptr, PAGE_SHIFT)
 #define page_unmask_bits(ptr) ptr_unmask_bits(ptr, PAGE_SHIFT)
-- 
2.9.5